igneous
Tumbled pegmatitic granite
Granite, chiefly quartz–feldspar–mica; likely altered pegmatite
AI-generated identification · may be incorrectCoarse, interlocking crystals with white to pale yellow feldspar/quartz, dark mica or amphibole, and reddish iron-oxide staining. Mohs hardness about 6–7; vitreous to pearly luster, no consistent cleavage as a whole, and specific gravity roughly 2.6–2.8.
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Physical properties
Coarse, interlocking crystals with white to pale yellow feldspar/quartz, dark mica or amphibole, and reddish iron-oxide staining. Mohs hardness about 6–7; vitreous to pearly luster, no consistent cleavage as a whole, and specific gravity roughly 2.6–2.8.
Formation & geological history
A plutonic igneous rock crystallized slowly from silica-rich magma deep in the crust, probably during a Precambrian-to-Phanerozoic intrusive event; later weathering and tumbling rounded it.
Uses & applications
Used as dimension stone, aggregate, countertops, and decorative landscaping material; polished pieces are inexpensive geological collectibles.
Geological facts
The large, visibly interlocking crystals indicate slow cooling, while rusty red patches reflect oxidation of iron-bearing minerals. Exact identification requires a fresh surface or thin section.
Field identification & locations
Identify by its granular texture, abundant quartz/feldspar, scattered dark minerals, and lack of layering or fossils; common in continental shields and granitic plutons worldwide.
